根據國內外不同案例的現地監測結果顯示,連續壁施工引致之地盤變位量,最大可達主體開挖所引起的總變位量30%~50%,根據上列所述可知連續壁構築過程對鄰房建物有一定的影響,然而影響連續壁構築過程造成土體位移量的因素甚多,這些影響的諸多變數甚難控制。本研究使用有限元素法軟體PLAXIS 3D ,針對連續壁施作過程進行地盤位移與槽溝穩定性分析,首先藉由網格密度、分析步驟與土體幾何邊界的比對,確定最佳研究方式後,再針對相關監測與數值分析案 例進行驗證,以瞭解本方法的適用性與準確性。 藉由本研究可以發現,B1∼B3 開挖階段的側向應力呈現接近或小於靜止土壓力K0 狀況下的側向應力,是為主動狀態趨勢。而C1∼C2 階段的側向應力則呈現大於或接近靜止土壓力狀況下的側向應力,稱此為土體的「恢復現象」。在不同階段槽溝整體的安全係數分析結果可以發現,隨著第一實刀的B1 階段至第三洗刀的B3 階段,安全係數逐階下降,其中最危險的階段為B3 階段,並隨著液態混凝土的注入(C1 階段)安全係數恢復至最安全的狀態。 本研究再針對台北松山層淡二區土層,進行連續壁施作過程影響因素分析,根據成果發現,連續壁單元厚度W 與單元深度D 對連續壁槽溝的地盤位移與槽溝穩定性影響不大。而對連續壁槽溝影響極大的參數包括:單元長度L、穩定液與地下水位液壓差△h、現地機具工作載重與多個單元施作過程等。最後本研究並訂定出台北松山層淡二區土層,連續壁施作過程垂直沈陷量影響範圍,在單一單元沿槽溝中心1/2 長度(x 向)影響範圍為12m( 2L), 垂直槽溝中心壁面(z 向)影響範圍為25m( 5/6D)。而五個單元的垂直沈陷量影響範圍, 沿槽溝中心1/2 長度(z 向)影響範圍為30m( 5/4TL 總槽溝長度); 垂直槽溝中心壁面(x 向)影響範圍為35m( 7/6D)。
Among today’s researches, feW of them involve the ground settlement resulted by the construction of diaphragm Wall. As a matter of fact, according to the monitoring data in domestic and foreign cases, the maximum ground settlement resulted by the construction of diaphragm Wall may account for 30%-50% of the total settlement. There are many factors may affect such settlement, most of them are difficult to control.This study use finite element softWare PLAXIS 3D,to analysis ground settlement and panel stability under construction of diaphragm. In the first, the parametric study is use to evaluate mesh gradient, research steps and geoeogy boundary. Secondy the numerical ressulte is compared With field monitoring data and also verifield accuracy of finite element method . The lateral earth pressure is smaller than earth pressure at rest during B1~B3 excavation stage, this is called the active state. At C1~C2 stage, the lateral earth pressure is larger than rest earth pressure. This is called the return to mostly passive state of ground. According to the results of panel stability analyses, the satety facter is grasdually loWer at B1~B3 excavation stage, and then returning to safe side at concreting stage. This study is also evaluated the influence facters at construction of diaphragm Wall of soil deposit in Taipei basin. It is founed that, the unit thickness W and unit depth D of diaphragm Without any. The unit length , grountWater level difference △h, Working load and construction stage and have great influence to panel stability. Finally, the study decided the influence range of diaphragm excavation stage of soil deposit in Taipei basin. In x direction, the influence range is 12meters (2L)at the centre of unit panel.In z direction,the influence range is 25 meters (5/6D)at the centre of unit panel otherWise,in z direction,the influence range is 30 meters(5/4 panel length).In x direction,the influence range is 35 meters(7/6 panel depth).